1. Field of the Invention
The present invention relates to metallic material on which a chromium-oxide passivation film is formed and a method for manufacturing the same, and a fluid supplying/exhaust system.
2. Description of the Related Art
In semiconductor manufacturing technology, gases with a hard corrosive action such as hydrogen chloride or hydrogen bromide or gases with a hard decomposing action such as silane, diborane, phosphine or the like have been used. Since gases hard in corrosivity easily corrode conventional stainless steel (SUS 316L) to result in metal contamination due to corrosion on semiconductor substrates, a semiconductor with high reliability has been difficult to manufacture.
Moreover, since the gases with the hard decomposing action are decomposed easily due to nickel in catalytic action on the stainless steel, the desired gases are difficult to supply with a desired concentration, semiconductors high in reliability have been difficult to manufacture. In recent years, a technology for forming a chromium-oxide passivation film has been introduced in order to solve the problems described above.
However, development of the metallic material, and surface treatment technology prior to oxidizing treatment or various technologies such as a technology supplying an oxidizing atmosphere such as temperature and a component ratio in oxidizing gases have been required in order to form the chromium-oxide passivation film. Therefore, it has been impossible to inexpensively form the chromium-oxide passivation film onto the optional metallic material and parts.
Moreover, although it has been a prior art technology, coating chromium for improvement of corrosion resistance, it has not been excellent since it is poor in adhesion, moreover, chromium has large internal stress, which causes cracks, so that corrosion is caused at an interface between metallic material and the coat film. Although a crack-free chromium coating technology has been developed in order to solve these cracks, fracture due to distortion during processing may occur since the film thickness is uneven, thereby causing corrosion.
Moreover, there has been problem that although a dual-layer chromium coating technology has been developed in order to solve this fracturing due to distortion, this technology uses different coating processes which results in an increase in cost, so that it is poor in productivity.
Moreover, there has been a technology that heat treatment is performed after metal coating. However, there have been problems in these technologies that vacancies (pin holes) exist on the surface after coating, the coat film may peel off, or the film obtained after heat treatment is a composite-oxide film or may have a property of ceramic, and since the metal material or the substrate layer is contact with corrosive gases when such vacancies exist, corrosion progresses on the interface between the metal of the substance layer and the coat film, and the desired corrosion resistance can not be obtained because of the composite-oxide film. Furthermore, it is poor in workability because it has the property of ceramic.
The object of the invention is to provide a metallic material on which a chromium-oxide passivation film (high in productivity) is formed and a method for manufacturing the same by forming this chromium-oxide passivation film, having excellent corrosion resistance, inexpensively and quickly.
The object of the invention is to provide parts contacting with fluid and a fluid supplying system capable of safely supplying safely fluid hard in corrosivity by forming the chromium-oxide film excellent in corrosion resistance without containing an oxide film of other metal.